Techniques for power transfer through wheels of a patient support apparatus

ABSTRACT

A power transfer system comprises a patient support apparatus and a separate power transfer device. The patient support apparatus comprises a support structure having a base and a patient support surface for a patient and wheels coupled to the support structure to facilitate movement of the patient support apparatus over a floor surface. One or more of the wheels includes a power receiver integrated therewith. The power transfer device is energizeable to interact with the wheel to facilitate power transfer between the power transfer device and the power receiver through the wheel.

CROSS-REFERENCE TO RELATED APPLICATION

The subject patent application claims priority to and all the benefitsof U.S. Provisional Patent Application No. 62/576,317 filed on Oct. 24,2017, the disclosure of which is hereby incorporated by reference in itsentirety.

BACKGROUND

Patient support apparatuses such as hospital beds, stretchers, cots,wheelchairs, and chairs are routinely used by operators to move patientsfrom one location to another. Conventional patient support apparatusescomprise a base and a patient support surface upon which the patient issupported. Wheels are coupled to the base to enable transport over floorsurfaces.

A significant number of patient support apparatuses are not powered.However, there is increasing demand to provide patient supportapparatuses with energy-consuming devices, such as motors, sensors, andelectronics. Conventionally, such energy is provided either by a primary(non-rechargeable) battery or a rechargeable battery. Primary batteriesrequire frequent replacement and add weight and cost to the patientsupport apparatuses. Rechargeable batteries require personnel to plugthe patient support apparatus to an external electrical outlet (orstation) for charging, thereby reducing availability for usage of thepatient support apparatus and inconveniently requiring the patientsupport apparatus to include an electrical power cord, which may beburdensome to manage. Thus, conventional energy systems for patientsupport apparatuses are undesirable for at least these reasons.

A patient support apparatus with features designed to overcome one ormore of the aforementioned challenges is desired.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is perspective view of a patient support apparatus according toone example.

FIG. 2 is block diagram of one example of a power transfer systemcomprising the patient support apparatus having a power receiverintegrated with one or more wheels and further comprising a separatepower transfer device energizable to interact with the wheel tofacilitate power transfer to the power receiver through the wheel.

FIG. 3 is a perspective view, partially in phantom, showing inductivepower transfer between the power transfer device and the power receiverof the wheel of the patient support apparatus, according to one example.

FIG. 4 is a perspective view, partially in phantom, showing capacitivepower transfer between the power transfer device and the power receiverof the wheel of the patient support apparatus, according to one example.

FIG. 5 is an assembly view of a tire and a rim of the wheel of thepatient support apparatus according to one example, wherein the tire andthe rim each include electrical receiving elements of the power receiveraligned with an exterior face of the wheel.

FIG. 6 is a perspective view, partially in phantom, of the powertransfer device comprising electrical sending elements on verticalmembers for interacting with opposing exterior faces of the wheel andwith the power transfer device including mechanical features to retainthe wheel for stationary power transfer.

FIG. 7 is a perspective view, partially in phantom, of the powertransfer device comprising a guide mechanism for guiding movement of thewheel and comprising electrical sending elements for interacting withelectrical receiving elements aligned with opposing exterior faces ofthe wheel for providing power transfer during wheel movement through theguide mechanism.

FIG. 8 is an assembly view of the tire and the rim of the wheel of thepatient support apparatus according to another example, wherein the tireand the rim each include electrical receiving elements of the powerreceiver aligned with a contact face of the wheel.

FIG. 9 is a top view, partially in phantom, of the power transfer devicecomprising another embodiment of the guide mechanism for guidingmovement of the wheel and comprising electrical sending elements on ahorizontal member being parallel with the floor surface for interactingwith the electrical receiving elements aligned with the contact face ofthe wheel for providing power transfer during wheel movement through theguide mechanism.

FIG. 10 is a perspective view, partially in phantom, of the powertransfer device comprising the horizontal member embodied as a floor mathaving electrical sending elements for interacting with electricalreceiving elements aligned with the contact face of the wheel.

FIG. 11 is an elevation view, partially in cross-section, illustratinginteraction between the electrical sending elements of the powertransfer device and the electrical receiving elements of the wheel ofFIG. 10.

FIG. 12 is a side view, partially in phantom, of the patient supportapparatus comprising electrical receiving elements integrated in thewheel and an unactuated brake mechanism providing electricaldisconnection of the electrical receiving elements to an electricalsystem of the patient support apparatus.

FIG. 13 is the view of FIG. 12, wherein the brake mechanism is actuatedto provide electrical connection between the electrical receivingelements and the electrical system of the patient support apparatus.

FIG. 14 is a perspective view of a wheel motor coupled to the wheel,wherein power receiver is embodied as, or integrated with, the wheelmotor.

FIG. 15 is an elevation view, partially in phantom of the wheel andwheel motor of FIG. 14 coupled to the patient support apparatus andinteracting with the power transfer device being embodied as a unit forrotating the wheel to transfer power to the wheel motor, according toone example.

FIG. 16 is an elevation view, partially in phantom of the wheel andwheel motor of FIG. 14 interacting with the power transfer device beingembodied as another example of a unit for rotating the wheel to transferpower to the motor.

DETAILED DESCRIPTION

I. Patient Support Apparatus Overview

Referring to FIG. 1, a patient support apparatus 30 is shown for movinga patient from one location to another. The patient support apparatus 30illustrated in FIG. 1 is a hospital bed. In other embodiments, however,the patient support apparatus 30 may be a stretcher, cot, wheelchair,chair, or similar apparatus.

A support structure 32 provides support for the patient during movementof the patient support apparatus 30. The support structure 32illustrated in FIG. 1 comprises a base 34 and an intermediate frame 36.The intermediate frame 36 is spaced above the base 34. The supportstructure 32 also comprises a patient support deck 38 disposed on theintermediate frame 36. The patient support deck 38 may comprise severalsections, some of which are pivotable relative to the intermediate frame36, such as a head section, a seat section, a thigh section, and a footsection. The patient support deck 38 provides a patient support surface42 upon which the patient is supported. The patient support surface 42is supported by the base 34.

A mattress 40 is disposed on the patient support deck 38. The mattress40 comprises a direct patient support surface 43 upon which the patientis supported. The base 34, intermediate frame 36, patient support deck38, and patient support surfaces 42, 43 each have a head end and a footend corresponding to the designated placement of the patient's head andfeet on the patient support apparatus 30. The construction of thesupport structure 32 may take on any suitable design, and is not limitedto that specifically set forth above or shown in FIG. 1.

Side rails 44, 46, 48, 50 are coupled to the intermediate frame 36. Afirst side rail 44 is positioned at a right head end of the intermediateframe 36. A second side rail 46 is positioned at a right foot end of theintermediate frame 36. A third side rail 48 is positioned at a left headend of the intermediate frame 36. A fourth side rail 50 is positioned ata left foot end of the intermediate frame 36. If the patient supportapparatus 30 is a stretcher or a cot, there may be fewer side rails. Theside rails 44, 46, 48, 50 are movable between a raised position in whichthey block ingress and egress into and out of the patient supportapparatus 30, one or more intermediate positions, and a lowered positionin which they are not an obstacle to enable such ingress and egress. Instill other configurations, the patient support apparatus 30 may notinclude any side rails.

A headboard 52 and a footboard 54 are coupled to the intermediate frame36. In other embodiments, when the headboard 52 and footboard 54 areincluded, the headboard 52 and footboard 54 may be coupled to otherlocations on the patient support apparatus 30, such as the base 34. Instill other embodiments, the patient support apparatus 30 does notinclude the headboard 52 or the footboard 54.

Operator (human control) interfaces 56, such as handles, are shownintegrated into the footboard 54 and side rails 44, 46, 48, 50 tofacilitate movement of the patient support apparatus 30 over the floorsurfaces. Additional operator interfaces 56 may be integrated into theheadboard 52 and/or other components of the patient support apparatus30. The operator interfaces 56 are graspable by the operator tomanipulate the patient support apparatus 30 for movement. The operatorinterface 56 may comprise one or more handles coupled to theintermediate frame 36. The operator interface 56 may simply be a surfaceon the patient support apparatus 30 upon which the operator locallyapplies force to cause movement of the patient support apparatus 30 inone or more directions, also referred to as a push location. This maycomprise one or more surfaces on the intermediate frame 36 or base 34.This could also comprise one or more surfaces on or adjacent to theheadboard 52, footboard 54, and/or side rails 44, 46, 48, 50. In otherembodiments, the operator interface 56 may comprise separate handles foreach hand of the operator. For example, the operator interface 56 maycomprise two handles. Other forms of the operator interface 56 are alsocontemplated.

One or more caster (wheel) assemblies 58 are coupled to the base 34 tofacilitate transport over floor surfaces. In one example, as shown inFIG. 1, four caster assemblies 58 a-58 d are arranged in each of fourquadrants of the base 34 adjacent to corners of the base 34. In theembodiment shown, the caster assemblies 58 a-58 d are able to rotate andswivel relative to the support structure 32 during transport.

The caster assemblies 58 may be non-steerable, steerable, non-powered,powered (driven), or any combinations thereof. The caster assemblies 58may have any suitable shape or configuration other than those shown inthe Figures.

The patient support apparatus 30 may comprise any suitable number ofcaster assemblies 58, such as two or six, etc. The caster assemblies 58may have any suitable configuration and arrangement depending on thespecific type of patient support apparatus 30. For example, when thepatient support apparatus 30 is a wheelchair, the patient supportapparatus 30 may comprise two front non-driven caster assemblies 58 andtwo rear driven caster assemblies 58.

The caster assembly 58 comprises one or more wheels that may be airless(non-pneumatic), inflatable, pneumatic or semi-pneumatic. The casterassembly 58 may be coupled to the base 34 according to any suitablemanner and using any suitable fastening mechanism. Caster assemblies 58and structures, functions and applications thereof may be like thosedescribed in U.S. Patent Application Publication No. 2016/0089283,entitled “Patient Support Apparatus,” the disclosure of which is herebyincorporated by reference in its entirety.

Additionally, one or more auxiliary wheels 66 (powered or non-powered)may be coupled to the support structure 32. The auxiliary wheel 66 maybe movable between a stowed position and a deployed position. In somecases, when these auxiliary wheels 66 are located between the casterassemblies 58 and contact the floor surface in the deployed position,they cause two of the caster assemblies 58 to be lifted off the floorsurface thereby shortening a wheel base of the patient support apparatus30. Such auxiliary wheels 66 may also be arranged substantially in acenter of the base 34.

The patient support apparatus 30 comprises a controller 68 incommunication with and for controlling any suitable components of thepatient support apparatus 30, such as the electrical orelectromechanical components described herein. The controller 68 maycomprise any suitable signal processing means, computer executableinstructions or software modules stored in non-transitory memory whereinthe executable instructions or modules may be executed by a processor,or the like. Additionally, or alternatively, the controller 68 maycomprise a microcontroller, a processor, one or more integratedcircuits, logic parts, and the like for enabling the same. Thecontroller 68 may have any suitable configuration for enablingperformance of various tasks related to operation of the patient supportapparatus 30, such as those described below. The controller 68 may belocated at any suitable location of the patient support apparatus 30.

As shown in FIG. 1, the patient support apparatus 30 may comprise one ormore steering motors 70 a-70 d for changing an orientation of the casterassemblies 58 about a swivel axis. The steering motor 70 may be coupledto the stem 60 of the caster assembly 58. Each steering motor 70 maychange the orientation of the caster assemblies 58 to facilitatesteering of the patient support apparatus 30. For example, the steeringmotors 70 may change the orientation of the caster assemblies 58 to helpmove patient support apparatus 30 in the direction desired by thecaregiver. One steering motor 70 may be associated with each casterassembly 58, and more specifically, the stem 60 of the caster assembly58. Alternatively, the steering motors 70 may be associated with onlycertain caster assemblies 58, e.g., the front-leading caster assemblies58 a, 58 b. The steering motors 70 may be located inside or outside therespective caster assembly 58.

The steering motors 70 may be coupled to the controller 68. The steeringmotors 70 may be directly wired to the controller 68 or in wirelesscommunication with the controller 68. The steering motors 70 may receivecontrol signals from the controller 68 commanding reorientation of therespective caster assemblies 58. For example, the control signals may bederived from the controller 68 receiving readings indicative of userapplied force and direction of force when pushing patient supportapparatus 30. Additional examples of control signals provided by thecontroller 68 to effect reorientation by the steering motors 70 aredescribed below. Steering motors 70 and techniques for generatingsignals for controlling the same may be like those described in U.S.Patent Application Publication No. 2016/0089283, entitled “PatientSupport Apparatus,” the disclosure of which is hereby incorporated byreference in its entirety.

A drive motor 72 a-72 e may be associated with the respective casterassembly 58 or with the auxiliary wheels 66, as shown in FIG. 1. Thedrive motor 72 is configured to cause the caster assembly 58 orauxiliary wheel 66 to rotate about the rotational axis R of the wheel.The drive motors 72 are coupled to the controller 68. The drive motors72 may be directly wired to the controller 68 or in wirelesscommunication with the controller 68. The drive motor 72 is configuredto cause the caster assembly 58 or auxiliary wheel 66 to rotate inresponse to receiving control signals provided by the controller 68. Forexample, the controller 68 may command the drive motor 72 to rotate therespective caster assembly 58 or auxiliary wheel 66 to effect a desiredvelocity for the patient support apparatus 30 based on user input and/orsensed readings relating to the environment of the patient supportapparatus 30. The drive motor 72 may be located inside of or coupled tothe outside of the respective caster assembly 58 or auxiliary wheel 66.Drive motors 72 and techniques for generating signals for controllingthe same may be like those described in U.S. Patent ApplicationPublication No. 2016/0089283, entitled “Patient Support Apparatus,” thedisclosure of which is hereby incorporated by reference in its entirety.

The patient support apparatus 30 further includes a braking system forthe caster assemblies 58 or auxiliary wheel 66. Specifically, a brakemechanism 74, as shown in FIG. 1, may be provided to engage/disengagebraking. The brake mechanism 74 may be manually positionable toengage/disengage braking. The braking mechanism 74 may include a pedal(as shown in FIG. 1), a handle, or the like. The braking system mayinterconnect more than one caster assembly 58 to provide simultaneousbraking thereof. Each caster assembly 58 can be associated with aspecific brake mechanism 74 or more than one device can be associatedwith one brake mechanism 74. The braking system may have any suitableconfiguration for the patient support apparatus 30. Examples of brakingsystems for the patient support apparatus 30 can be like those describedin U.S. Pat. No. 8,006,332, entitled “Hospital Bed,” the disclosure ofwhich is hereby incorporated by reference in its entirety.

The patient support apparatus 30 requires power for energizing one ormore electrically powered devices coupled to the patient supportapparatus 30, such as those described above, in addition to any displaydevices, sensors, actuators, sub-systems (e.g., patient scale system),and the like. In one embodiment, the patient support apparatus 30comprises an energy storage device 76, as shown in FIG. 1, which iscoupled to the one or more devices through an electrical distribution ofthe patient support apparatus 30. The energy storage device 76 may beany suitable device for storing energy to power the electrical devices.For example, the energy storage device 76 may be a battery, such as aLead-acid or Lithium ion battery, a capacitor (such as a supercapcitor),or the like. The energy storage device 76 may be a primary cell (oneuse) or a rechargeable cell (more than one use). The energy storagedevice 76 may be disposed at any suitable location on the patientsupport apparatus 30 or components thereof. For example, as shown inFIG. 1, the energy storage device 76 is fixed to the base 34. Thepatient support apparatus 30 may comprise any number of energy storagedevices 76, which may be of a similar type or of different types. Thecontroller 68 may comprise and/or control switches, relays, logic,circuits or any other suitable hardware and/or software for managingenergy supplied to and/or energy discharged from the energy storagedevice 76. The energy storage device 76 may be of any suitableconfiguration for powering the devices of the patient support apparatus30.

II. Power Transfer Techniques

In accordance with FIGS. 2-16, techniques are shown for transferringpower to the patient support apparatus 30. As will be understood fromthe various embodiments below, power is transferred wirelessly to thepatient support apparatus 30. In other words, power is transferred tothe patient support apparatus 30 without using a direct electrical andphysical connection to the patient support apparatus 30 using aconductive wire/cable/cord (such as an electrical cord that is pluggedinto an electrical outlet). As used herein, the term “wireless” relatesto the transfer of power and may embody various wireless techniques fortransferring power to the patient support apparatus 30, such aselectrical, inductive, electromagnetic, and mechanical techniques, asshown in FIG. 2. Thus, the term “wireless” is not limited to radiofrequency or microwave signal transfer, as generally used incommunication systems.

As shown in FIG. 2, a power transfer system 80 is provided to implementwireless transfer of power. The power transfer system 80 includes thepatient support apparatus 30 and a power transfer device 82. The powertransfer device 82 is separate and otherwise independent from thepatient support apparatus 30. In other words, the power transfer device82 is external to the patient support apparatus 30, rather than beingintegrated therewith.

The power transfer device 82 is configured to interact with the patientsupport apparatus 30 to enable wireless power transfer thereto. As willbe understood from the embodiments below, such interaction may beimplemented according to various techniques, which avoid direct-wiredelectrical connection. The power transfer device 82 is energizable tointeract with the patient support apparatus 30. Thus, the power transferdevice 82 is not simply passively interacting with the patient supportapparatus 30, but is rather actively energized to interact therewith. Asshown in FIG. 2, the power transfer device 82 may be coupled to, orotherwise include, a power supply 84. The power transfer device 82 maybe energized using energy from the power supply 84. The power supply 84may be any suitable source of power, such as another energy storagedevice (battery, etc.) or may be general-purpose alternating-current(AC) electric power supply of a facility, such as a hospital, or thelike. It is to be appreciated that the power transfer device 82 may beenergized using any other source of power besides electrical power, suchas mechanical and/or chemical-based power, or the like.

As shown in FIG. 2, the patient support apparatus 30 comprises a powerreceiver 86. The power receiver 86 is configured to interact with thepower transfer device 82 to facilitate wireless power transfer to thepatient support apparatus 30 from the power transfer device 82. The term“receiver” in power receiver 86 is not limited to only receiving power.Additionally or alternatively, the power receiver 86 may generate(produce) or transduce (convert) power in response to interactionbetween the power transfer device 82 and the patient support apparatus30. Examples of the power receiver 86 are described in variousembodiments below.

The energy storage device 76 of the patient support apparatus 30 may becoupled to the power receiver 86. The power receiver 86 is configured toprovide power received from transfer using the power transfer device 82to the energy storage device 76 such that the energy storage device 76can be charged for energizing any of the powered devices of the patientsupport apparatus 30.

In accordance with FIGS. 2-16, the power receiver 86 is integratedspecifically with one or more of the wheels 58, 66 of the patientsupport apparatus 30. The power transfer device 82 interacts with one ormore of the wheels 58, 66. Thus, the power transfer device 82facilitates power transfer to the power receiver 86 through one or moreof the wheels 58, 66.

The wheel 58, 66 that includes the power receiver 86 may be one or morecaster assembly 58, the auxiliary wheel 66, or any other wheel thatfacilitates movement of the patient support apparatus 30 along the floorsurface. The power receiver 86 may be integrated with any activelysteerable wheel, any actively driven wheel, any passive wheel, or thelike. A separate power receiver 86 may be integrated with any number ofwheels 58, 66. In one embodiment, a separate power receiver 86 may beintegrated with each of the four caster assemblies 58 a-58 d in FIG. 1.Additionally or alternatively, any wheel 58, 66 may integrate any numberof power receivers 86.

Furthermore, an entirety of the power receiver 86 and any componentsthereof, may be integrated with the wheel 58, 66. Alternatively, primarypower receiving components of the power receiver 86 may be integratedwith the wheel 58, 66, while secondary components of the power receiver86, such as ancillary components or electrical connections, are locatedelsewhere other than the wheel 58, 66, such as on the support structure32, with the controller 68, or the like. In either situation, the powerreceiver 86 is integrated with the wheel 58, 66 so that power istransferred to the patient support apparatus 30 using the wheel 58, 66.Integration of the power receiver 86 with the wheel 58, 66 may befurther understood from the various examples below.

The power receiver 86 may be integrated into any suitable part of thewheel 58, 66. For example, the power receiver 86 may be integrated withany one or more of a motor 70, 72, a tire 88, a rim 90 (hub), an axle 92of the wheel 58, 66, and the like. The power receiver 86 also may beintegrated into a stem of the caster assembly 58, which couples to thebase 34.

In any of the embodiments described herein, electrical coupling is madeto the wheel 58, 66 to energize or activate the power receiver 86 andany components associated therewith that are integrated with the wheel58, 66. Such electrical coupling may be wireless or wired and may berouted through any suitable part of the wheel 58, 66, such as throughthe motor 70, 72, the tire 88, the rim 90, the axle 92, and the like.Examples of such electrical coupling, and techniques for interruptingsuch coupling, are described below.

As shown in embodiments of FIGS. 3-13, wireless power transfer isimplemented using electrically driven power transfer between the powertransfer device 82 and the power receiver 86 of the wheel 58, 66.Specifically, electrically driven power transfer may be implementedusing inductive power transfer and/or capacitive power transfer. Toimplement these techniques, the patient support apparatus 30 is movedtowards the power transfer device 82 such that the wheel 58, 66, andhence, the power receiver 86 is proximate to the power transfer device82 in a spaced apart relationship. The power transfer device 82 and thepower receiver 86 each are equipped with energizable electricalelements. The power transfer device 82 is energized and inductive and/orcapacitive interaction is created between the electrical elements of thepower transfer device 82 and the power receiver 86. Power is transferredto the power receiver 86 in response to the inductive and/or capacitiveinteraction.

As for inductive power transfer, and referring to FIG. 3, the powertransfer device 82 comprises a sending coil 94 and the power receiver 86comprises a receiving coil 96. Inductive power transfer occurs from thesending coil 94 to the receiving coil 96. The coils 94, 96 are eachelectrical inductors and are operable together to form a transformer.The power transfer device 82 may comprise a transmitter circuit 98, suchas an oscillator, coupled to the power supply 84 for energizing thesending coil 94 using AC current. As the AC current passes through thesending coil 94, a magnetic field (B) is generated and passes throughthe receiving coil 96. Upon wirelessly receiving the magnetic field (B),the receiving coil 96 induces AC current. The power receiver 86 maycomprise a receiver circuit 100 for receiving the AC current induced bythe receiving coil 96. For example, the receiver circuit 100 may be arectifier circuit for converting the AC current into DC current suitablefor the patient support apparatus 30 and/or energy storage device 76.

In some embodiments, one or both coils 94, 96 may be tuned or otherwiseequipped with electrical components for enabling resonant inductivecoupling therebetween. In such situations, the coils 94, 96 resonate ata common resonant frequency for increasing the effectiveness of powertransfer. It should be appreciated that inductive coupling between thepower transfer device 82 and the power receiver 86 may be implementedaccording to other techniques. Furthermore, the coils 94, 96, thetransmitter circuit 98, and the receiver circuit 100 may have any otherconfiguration or geometry for enabling inductive power transfer.

For capacitive power transfer, and referring to FIG. 4, the powertransfer device 82 comprises a sending plate 102 and the power receiver86 comprises a receiving plate 104. Capacitive power transfer occursfrom the sending plate 102 to the receiving plate 104. The plates 102,104 are each electrical conductors (e.g., electrodes) and are operabletogether to form a capacitor. The transmitter circuit 98 applies ACvoltage to the sending plate 102. In turn, an electric field (E) isgenerated and passes to the receiving plate 104. Upon wirelesslyreceiving the electric field (E), the receiving plate 104 induces ACvoltage. The receiver circuit 100 utilizes the AC voltage to facilitatethe flow of AC current suitable for the patient support apparatus 30and/or energy storage device 76.

In FIG. 4, each of the power transfer device 82 and the power receiver86 comprise one plate 102, 104 thereby implementing a unipolarconfiguration. Here, the power transfer device 82 and the power receiver86 each comprise a passive grounding electrode (not shown) for providingan electrical return path for the AC current back to the power transferdevice 82. Thus, energy is transferred in one direction between theplates 102, 104, i.e., from plate 102 to plate 104. For the powerreceiver 86, the passive grounding electrode may be the base 34 of thepatient support apparatus 30, a conductive portion of the wheel 58, 66or any other conductive element providing electrical grounding.

However, in other embodiments, a bipolar configuration may beimplemented wherein the each of the power transfer device 82 and thepower receiver 86 comprise two plates 102 a, 102 b and 104 a, 104 b,corresponding with each other, respectively. The electrical field (E)passes through one pair of plates 102 a, 104 a to create AC current atthe power receiver 86 and then the electrical field (E) passes throughthe second pair of plates 102 b, 104 b to return AC current at the powertransfer device 82, and so on. Thus, energy is transferredbi-directionally, in a looped-fashion, between the respective platepairs 102 a, 104 a and 102 b, 104 b.

In some embodiments, one or both plates 102, 104 may be tuned orotherwise equipped with electrical components for enabling resonantcapacitive coupling therebetween. It should be appreciated thatcapacitive coupling between the power transfer device 82 and the powerreceiver 86 may be implemented according to other techniques.Furthermore, the plates 102, 104, the transmitter circuit 98, and thereceiver circuit 100 may have any other configuration or geometry forenabling capacitive power transfer.

For simplicity, each of the embodiments of FIGS. 5-11 show inductivemeans of transferring power using the coils 94, 96. However, based onthe similarities in inductive and capacitive power transfer techniquesusing spaced apart and wireless means of transferring power betweenopposing electrical elements, those skilled in the art appreciate thatthe coils 94, 96 in any of FIGS. 5-11 may be replaced with the plates102, 104 to illustrate capacitive power transfer. In other words,capacitive power transfer is fully contemplated for each of theseexamples. It should be understood that the specific geometries of thecoils 94, 96 and/or specific integration of the coils 94, 96 with thewheel 58, 66 may differ from specific geometries and/or integration ofthe plates 102, 104 for each of these examples. This is due to thenature of inductive power transfer requiring coils and capacitive powertransfer requiring plates for proper operation. However, those skilledin the art can readily recognize specific geometries and/or integrationof the plates 102, 104 in view of the teachings described hereinrelating to the coils 94, 96. To capture this commonality, the coils 94,96 and/or the plates 102, 104 in the embodiments described below arereferred to as electrical receiving elements when integrated with thepower receiver 86 and electrical sending elements when integrated withthe power transfer device 82.

Referring to FIG. 5, two examples are shown wherein the power receiver86 is integrated with the wheel 58, 66 of the patient support apparatus30. In one example, the power receiver 86 a is integrated with the tire88 and in the other example the power receiver 86 b is integrated withthe rim 90 supporting the tire 88. Specifically, an electrical receivingelement of the power receiver 86, such as the receiving coil 96 a, 96 bis integrated with the tire 88 and integrated with the rim 90. Theseexamples may be implemented individually or in combination.

Wireless power transfer through the wheel 58, 66 in these examples takesadvantage of the wheel 58, 66 being rotatable about an axis of rotation(R). For example, in both examples in FIG. 5, the electrical receivingelement 96 is disposed radially about the axis of rotation R. Therefore,the electrical receiving element 96 rotates with rotation of the wheel58, 66. This allows predictable exposure to the electrical receivingelement 96 and effective power transfer to the electrical receivingelement 96, whether the wheel 58, 66 is stationary or rotating.

In the examples of FIG. 5, the wheel 58, 66 comprises an exterior face110 that is perpendicular to the floor surface. In other words, theexterior face 110 is the disc-shaped part of the wheel 58, 66 that isperpendicular to the axis of rotation R of the wheel 58, 66. Here, theelectrical receiving element 96 of the power receiver 86 comprises anarea, or a footprint, that is aligned with the exterior face 110. Forexample, the electrical receiving element 96 is disposed parallel to theexterior face 110. Therefore, the electrical receiving element 96 isperpendicular to the axis of rotation R of the wheel 58, 66. In theexample with the tire 88, the receiving element 96 is integrateddirectly on or behind the exterior face 110. In the example with the rim90, the electrical receiving element 96 is disposed directly on aportion of the rim 90 that is exposed to the exterior face 110. Theelectrical receiving element 96 may be integrated with the tire 88and/or rim 90 according to other techniques.

Since the electrical receiving element 96 is aligned with the exteriorface 110, the power transfer device 82 can interact with the exteriorface 110 of the wheel 58, 66 to establish coupling to the electricalreceiving element 96. Furthermore, since the electrical receivingelement 96 is aligned with the exterior face 110, at least some portionof the electrical receiving element 96 is raised vertically off thefloor surface.

Accordingly, as shown in FIGS. 3, 4, 6 and 7, the power transfer device82 comprises a vertical member 112 being perpendicular to the floorsurface. The vertical member 112 comprises one or more electricalsending elements 94, e.g., the sending coil 94 or the sending plate 102,which are raised vertically off the floor surface. The electricalsending element 94 of the vertical member 112 may be elevated to apredetermined height to correspond to the known height of the electricalreceiving element 96 relative to the wheel 58, 66. In some examples, thevertical member 112 may allow for manual or automatic adjustment of theheight of the electrical receiving element 96 for various size wheels58, 66. When the wheel 58, 66 is moved adjacent to the vertical member112, interaction between the exterior face 110 and the vertical member112 occurs to facilitate interaction between the electrical receivingelement 96 of the power receiver 86 and the electrical sending element94 of the power transfer device 82 to transfer power. The electricalsending elements 94 and the electrical receiving elements 96 may haveconfigurations other than those shown in the Figures.

In one example, the vertical member 112 of the power transfer device 82is installed into a fixture or wall of a facility. In other examples,the vertical member 112 is coupled to a docking station for the patientsupport apparatus 30. The vertical member 112 may also be on astationary or mobile unit.

In the example of FIG. 6, the wheel 58, 66 comprises two electricalreceiving elements 96 a, 96 b each aligned with respective opposingexterior faces 110 a, 110 b of the wheel 58, 66. The power transferdevice 82 comprises two vertical members 112 a, 112 b respectivelycomprising electrical sending elements 94 a, 94 b. The electricalsending elements 94 a, 94 b are configured to interact respectively withelectrical receiving elements 96 a, 96 b for effectively doubling thepower transfer capabilities for a single wheel 58, 66. Of course, onevertical member 112 may be used instead of two.

In this example, the power transfer device 82 interacts with the wheel58, 66 when the wheel 58, 66 is stationary and power transfer occursbetween the power transfer device 82 and the power receiver 86 when thewheel 58, 66 is stationary. Specifically, the power transfer device 82may comprise a stop 114 being configured to stop movement of the wheel58, 66 to align the power receiver 86 of the wheel 58, 66 with the powertransfer device 82. In this example, the power transfer device 82surrounds the wheel 58, 66. The power transfer device 82 may furtherinclude one or more mechanical features 116, such as grooves orchannels, for capturing the wheel 58, 66 therein or for rotating thecaster assembly 58 to establish proper stationary wheel alignment forpower transfer. The power transfer device 82, vertical member 112, stop114, and mechanical features 116 may have configurations other thanthose shown in the figures.

In some embodiments, the power transfer device 82 is configured tointeract with the wheel 58, 66 to facilitate power transfer between thepower transfer device 82 and the power receiver 86 when the wheel 58, 66is moving. The power transfer device 82 extends along the floor surfaceaccording to any suitable length to enable power transfer to the movingwheel 58, 66. The power transfer device 82 interacting with the movingwheel 58, 66 may be suitable for locations in a facility where frequentmoving traffic for patient support apparatuses 30 occurs, such ashallways, doorways, elevators and the like.

In the example of FIG. 7, the power transfer device 82 comprises a guidemechanism 120 configured to mechanically receive the wheel 58, 66 duringmovement thereof. The wheel 58, 66 comprises two electrical receivingelements 96 a, 96 b each aligned with respective opposing exterior faces110 a, 110 b of the wheel 58, 66. The power transfer device 82 comprisestwo vertical members 112 a, 112 b, which define walls of the guidemechanism 120. The vertical members 112 a, 112 b extend along the floorsurface according to any suitable length to enable power transfer to themoving wheel 58, 66. The vertical member 112 a, 112 b may be of a heightsuitable to enable power transfer, yet low enough so as to not interferewith movement of the patient support apparatus 30. The vertical members112 a, 112 b each respectively comprise a plurality of electricalsending elements 94 disposed along the length. The guide mechanism 120may comprise an entry 122, which reduces in width to guide the wheel 58,66 to the vertical members 112 a, 112 b. The electrical sending elements94 a, 94 b are configured to interact respectively with the electricalreceiving elements 96 a, 96 b as the wheel 58, 66 moves through thevertical members 112 a, 112 b. Of course, one vertical member 112 may beused instead of two. Furthermore, the guide mechanism 120 and entry 122may have configurations other than those shown in the figures.

In other examples, the power transfer device 82 may be mobile tointeract with the moving wheel 58, 66. For example, the power transferdevice 82 may comprise its own wheels and may be configured to latch onto any suitable part of the patient support apparatus 30, such as thebase 34. Such latching may occur manually by operator assistance, or mayoccur automatically by a controller integrated with the power transferdevice 82. Once latched, the power transfer device 82 is configured tomove along the floor surface with movement of the patient supportapparatus 30, and consequently, the wheel 58, 66. After latching, theelectrical sending element 94 of the power transfer device 82 ismaintained at a fixed, spaced apart, distance from the electricalreceiving element 96 of the wheel 58, 66 for facilitating couplingtherebetween while the wheel 58, 66 moves. Even though the powertransfer device 82 moves along with the patient support apparatus 30 inthis example, the electrical sending element 94 may rotate or may befixed from rotation.

Referring to FIG. 8, two additional examples are shown wherein the powerreceivers 86 a, 86 b are integrated respectively with the tire 88 andthe rim 90 of the wheel 58, 66. In the examples of FIG. 8, the wheel 58,66 comprises a contact face 128 that directly contacts the floor surfacewhen the wheel 58, 66 is stationary or moving. The contact face 128 isthus parallel to, or tangentially touching, the floor surface whencontacting the floor surface. The contact face 128 is disposed aroundthe axis of rotation R of the wheel 58, 66. Here, the electricalreceiving element 96 a of the power receiver 86 a comprises an area, ora footprint, that is aligned with, or otherwise disposed parallel to,the contact face 128. Therefore, the electrical receiving element 96 afaces the floor surface when the contact face 128 faces the floorsurface.

In the example with the tire 88, the electrical receiving elements 96 bare integrated with the tire 88, such as within or on an interior layerof the tire 88, and are disposed around the axis of rotation R andaligned with the contact face 128. In the example with the rim 90, theelectrical receiving elements 96 b are disposed on the rim 90 and aroundthe axis of rotation R and aligned with the contact face 128.Comparatively, when the aligned portion of the contact face 128 touchesthe floor surface, the electrical receiving elements 96 a in the tire 88example would be closer to the floor surface than the electricalreceiving elements 96 b in the rim 90 example.

Since the electrical receiving element 96 is aligned with the contactface 128 in this example, the power transfer device 82 can interact withthe contact face 128 to establish coupling to the electrical receivingelement 96. Accordingly, as shown in FIGS. 9-11, the power transferdevice 82 comprises a horizontal member 130 being aligned with, orotherwise parallel to, the floor surface. The horizontal member 130 canbe placed on the floor surface or integrated within the floor. Thehorizontal member 130 comprises one or more electrical sending elements94, which are also aligned with the floor surface.

When the wheel 58, 66 moves over the horizontal member 130, interactionbetween the contact face 128 and the horizontal member 130 occurs tofacilitate interaction between the electrical receiving element 96 andthe electrical sending element 94 to transfer power. The electricalsending elements 94 of the horizontal member 130 may be spaced apartfrom one another and/or geometrically sized to correspond to theelectrical receiving elements 96. The electrical sending elements 94 andthe electrical receiving elements 96 may be of different sizes or ofrelatively the same size and may have configurations other than thoseshown in the Figures.

The horizontal member 130 may be configured to interact with the wheel58, 66 when the wheel 58, 66 is moving to facilitate power transfer whenthe wheel 58, 66 is moving. In other examples, the horizontal member 130interacts with the wheel 58, 66 when the wheel 58, 66 is stationary suchthat power transfer occurs when the wheel 58, 66 is stationary. Ineither scenario, the horizontal member 130 may be suitable for locationsin a facility where frequent traffic for patient support apparatuses 30occurs, such as hallways, doorways, elevators, docking locations,charging stations, and the like. The horizontal member 130 of the powertransfer device 82 may be installed into a fixture of a facility. Inother examples, the horizontal member 130 is coupled to a dockingstation for the patient support apparatus 30. The horizontal member 130may be on a stationary or mobile unit.

In the example of FIG. 9, the power transfer device 82 comprises theguide mechanism 120 configured to mechanically receive the wheel 58, 66during movement thereof. The wheel 58, 66 comprises electrical receivingelements 96 aligned with the contact face 128. The power transfer device82 comprises the horizontal member 130 disposed within the guidemechanism 120, e.g., between opposing guide walls. The horizontal member130 comprises a plurality of electrical sending elements 94 disposedalong the length. The horizontal member 130 may extend along the floorsurface according to any suitable length and may comprise anyappropriate width to accommodate one or more wheels 58, 66 to enablepower transfer to the moving wheel 58, 66.

The electrical sending elements 94 are configured to interactrespectively with the electrical receiving elements 96 as the wheel 58,66 moves over the horizontal member 130. Of course, any number ofhorizontal members 130 may be used instead of one. The horizontal member130 and guide mechanism 120 may have configurations other than thoseshown in the figures. Furthermore, the embodiment of FIG. 9 may becombined with the embodiment of FIG.7 to provide the guide mechanism 120with electrical sending elements 94 in both the vertical members 112 a,112 b and the horizontal member 130 to provide increased power transfer.

In FIG. 10, the horizontal member 130 is embodied as a floor mat 132, asshown. The floor mat 132 comprises an array of electrical sendingelements 94 disposed in any suitable pattern. The pattern of electricalsending elements 94 may be different from that shown in FIG. 10. Forexample, certain electrical sending elements 94 may be encompassed byothers. Furthermore, the electrical sending elements 94 may be ofvarious sizes and/or geometries based on factors, such as anticipatedinteraction of the wheel 58, 66 with the floor mat 132, geometry of thewheel 58, 66, properties of the electrical sending elements 94, and thelike. The floor mat 132 may be coupled to the power supply 84 to provideenergy to the electrical sending elements 94. The floor mat 132 may haveany suitable geometric shape, such as an elongated rectangular shape, acurved shape, or the like. The floor mat 132 may also have portions thatare not aligned with the floor surface, but rather extend above thefloor surface, such as along an adjacent wall, or the like. The opennature of the floor mat 132 allows easy entry and exit of the wheel 58,66 from any direction. As such, the floor mat 132 may provide powertransfer whether the wheel 58, 66 is stationary or moving.

FIG. 11 is an elevation view, partially in cross-section, illustratingan example of interaction between the electrical sending elements 94 ofthe floor mat 132 and the electrical receiving elements 96 of the wheel58, 66. The contact face 128 of the wheel directly contacts the floormat 132. Spacing between the electrical sending elements 94 of the floormat 132 and the electrical receiving elements 96 of the wheel 58, 66exists because of the thickness of the contact face 128 and thethickness of floor mat 132 encompassing the electrical sending elements94. Between this spacing, power, e.g., inductive or capacitive, iswirelessly transferred between the elements 94, 96, as described. Aswith any other embodiment described herein, one or more electricalsending elements 94 may interact with one or more electrical receivingelements 96. Transfer of power will vary depending upon the position andorientation of the wheel 58, 66 relative to the floor mat 132.

In yet another example, the horizontal member 130 may be integrated intothe power transfer device 82 such as that shown in FIG. 6. Specifically,electrical sending elements 94 may be included in the mechanicalfeatures 116, such as grooves or channels, that capture the wheel 58, 66to establish stationary power transfer. Furthermore, when the electricalreceiving elements 96 are aligned with the contact face 128 of the wheel58, 66, the stop 114 in FIG. 6 may be equipped with one or moreelectrical sending elements 94 to establish power transfer to theelectrical receiving elements 96 when the wheel 58, 66 is stationary.

Power may be transferred to any number of wheels 58, 66 of the patientsupport apparatus 30 simultaneously or individually. For example, whenthe patient support apparatus 30 comprises four caster assemblies 58a-58 d and one or more auxiliary wheels 66, such as is shown in FIG. 1,power may be transferred simultaneously to each of the four casterassemblies 58 a-58 d and the one or more auxiliary wheels 66. Taking theembodiment of FIG. 10 for example, the four caster assemblies 58 a-58 dand the auxiliary wheel 66 may simultaneously rest upon the floor mat132. In such situations, the caster assemblies 58 a-58 d would providefour points of receiving power transfer and the auxiliary wheel 66 wouldprovide an additional fifth point of receiving power transfer. As such,with these several points of power transfer, there exists a hightolerance for alignment between the power receivers 86 and the floor mat132.

Moreover, the auxiliary wheel 66 may be of a greater size (e.g.,diameter and width) than the size of the caster assemblies 58 a-58 d. Assuch, in view of the power receiver 86 configurations described herein,the power transfer capabilities may be greater for the auxiliary wheels66 as compared with the caster assemblies 58 a-58 d. When used inconjunction, such as with the floor mat 132 of FIG. 10, the casterassemblies 58 a-58 d may each provide a lesser amount of power transferwhile the auxiliary wheel 66 provides a greater amount of powertransfer. Such variability enables the patient support apparatus 30 toreceive power in a balanced, dynamic fashion.

As described, electrical coupling is made to the wheel 58, 66 toenergize the power receiver 86 and any components associated therewiththat are integrated with the wheel 58, 66, such as the electricalreceiving elements 96. It may be desirable to energize the powerreceiver 86 in certain scenarios and not to energize the power receiver86 in other scenarios. Preventing activation of the power receiver 86may be desirable to reduce electromagnetic interference with surroundingdevices and/or to minimize consumption of power of the patient supportapparatus 30 when not transferring power.

Referring to FIGS. 12 and 13, one configuration is shown whereby suchelectrical coupling to the power receiver 86 is selectively controlled.In this example, selective coupling is triggered by actuation of thebrake mechanism 74. As shown in FIG. 12, first and second brakingelements 134, 136 are integrated with the wheel 58, 66. The firstbraking element 134 may rotate with the wheel 58, 66 while the secondbraking element 136 remains stationary relative to rotation of the wheel58, 66. Alternatively, the second braking element 136 may also rotatewith rotation of the wheel 58, 66. The braking elements 134, 136 areconfigured to engage each other mechanically to provide braking. Forexample, as shown, the braking elements 134, 136 comprise correspondingteeth for engagement. In FIG. 12, the second braking element 136 isdisengaged from the first braking element 134. The braking elements 134,136 may be configured to engage each other using means other thanmechanical engagement, such as electromagnetic engagement, or the like.

The braking elements 134, 136 are at least partially electricallyconductive to allow transfer of electrical current therethrough. Theelectrical receiving elements 96 of the power receiver 86 are eachelectrically connected to one of the braking elements 134, 136. Morespecifically, the electrical receiving elements 96 are coupled to thefirst braking element 134 in this example. The second braking element136 is electrically connected to the power distribution system of thepatient support apparatus 30, and may be connected, more specifically,to the receiver circuit 100 for the power receiver 86. Since the secondbraking element 136 is disengaged from the first braking element 134when the brake mechanism 74 is not actuated in FIG. 12, there remains anopen circuit such that the electrical receiving elements 96 are notenergized.

In FIG. 13, the brake mechanism 74 is actuated such that the secondbraking element 136 engages the first braking element 134. In turn, theteeth of the braking element 134, 136 engage each other to lock thewheel 58, 66. Through this engagement, electrical contact is establishedbetween the braking elements 134, 136. As a result, the electricalreceiving elements 96 can be energized through the braking elements 134,136.

Those skilled in the art appreciate that FIGS. 12 and 13 show only oneexample of the braking mechanism 74 and braking elements 134, 136, andthat the braking system or components thereof may be of any othersuitable configuration to stop movement of the wheel 58, 66. Forexample, the braking elements 134 may be a brake pad and a rotor thatselectively engage each other during braking, establishing electricalcontact therebetween.

Furthermore, it should be appreciated that the power receiver 86 may beselectively energized using means other than the braking system for thewheel 58, 66. For example, the electrical receiving elements 96 may bedirectly wired through the wheel 58, 66 to the controller 68, which canselectively switch on/off any of the electrical receiving elements 96using any suitable software or hardware control and based on sensorinput.

In the embodiments of FIGS. 3-13, power is transferred to the wheel 58,66 wirelessly using inductive and/or capacitive coupling techniques.However, wireless power transfer may occur using mechanical orelectromechanical power transfer techniques.

Referring to FIG. 14, one embodiment is shown wherein the power receiver86 comprises a wheel motor 70, 72 coupled to, or otherwise integratedwith the wheel 58, 66. The wheel motor 70, 72 may be the steering motor70 and/or drive motor 72 as described above. In some examples, the wheelmotor 70, 72 is dedicated solely for power transfer purposes through thewheel 58, 66.

The wheel motor 70, 72 is configured to receive power from rotation ofthe wheel 58, 66 to convert mechanical power into electrical power. Whenused in this manner, the wheel motor 70, 72 maybe understood as tofunction as a motor-generator. The wheel motor 70, 72 may comprise astationary component, such as a stator, and a rotational component, suchas an armature or rotor, that moves in response to the mechanical powerapplied thereto. The wheel motor 70, 72 may be any suitable type ofmotor that can generate power from wheel rotation, such as a brushlessor brushed motor, and the like.

When the motor 70 is the drive motor 72, the motor 72 receives powerduring rotation of the wheel 58, 66 about its rotational axis R. Whenthe motor 70 is the steering motor 70, the motor 70 receives powerduring rotation of the wheel 58, 66 about the swivel axis of the wheel58, 66. Wheel motors 70, 72 can also function as both dynamic andparking brakes, as well as provide regenerative braking.

In FIGS. 15 and 16, examples are shown wherein the power transfer device82 is energizable to rotate the wheel 58, 66 for rotating the wheelmotor 70, 72 to enable power transfer. More specifically, the powertransfer device 82 is electrically energized to create mechanical power.The mechanical power is transferred to the wheel 58, 66, andconsequently the wheel motor 70, 72, to mechanically move the same. Themechanical power that rotates the wheel 58, 66 is converted intoelectrical power by virtue of the electromagnetic induction, or thelike, occurring with movement of the wheel motor 70, 72.

In FIGS. 15 and 16, the power transfer device 82 comprises one or moretransfer motors 148 a, 148 b configured to move in response toelectrical actuation. In the embodiments shown in FIGS. 15 and 16, thetransfer motors 148 a, 148 b are rotational motors. The transfer motors148 a, 148 b are each coupled to a mechanical transfer element 150 a,150 b. The mechanical transfer elements 150 a, 150 b move in response toactuation of the transfer motors 148 a, 148 b. In the embodiments shownin FIGS. 15 and 16, the mechanical transfer elements 150 a, 150 b arerotational elements.

The embodiment of FIG. 15 provides the power transfer device 82 in adyno-type configuration, wherein the mechanical transfer elements arebarrels 150 a, 150 b. The contact face 128 of the wheel 58, 66 restsdirectly upon both barrels 150 a, 150 b. The barrels 150 a, 150 b rotatefrom actuation of the transfer motors 148 a, 148 b. In turn, this causesthe wheel 58, 66 to rotate. Rotation of the wheel 58, 66 createsrotation of the wheel motor 70, 72, thereby enabling power generationfor the patient support apparatus 30. Although the wheel 58, 66 rotates,the patient support apparatus 30 remains stationary. It should beappreciated that one barrel 150 may be utilized instead of two.Furthermore, the power transfer device 82 in this configuration may beinstalled into the floor or may be a unit that is placed on top of thefloor surface.

The embodiment of FIG. 16 provides the power transfer device 82 in atreadmill-type configuration, wherein the mechanical transfer elementsare flywheels 150 a, 150 b. The power transfer device 82 furthercomprises a contact belt 160 that is wrapped around the flywheels 150 a,150 b according to a frictional fit. The contact face 128 of the wheel58, 66 rests directly upon the contact belt 160. The flywheels 150 a,150 b rotate from actuation of the transfer motors 148 a, 148 b. Inturn, this causes the contact belt 160 to rotate about the flywheels 150a, 150 b. Rotation of the contact belt 160 causes the wheel 58, 66 torotate. Rotation of the wheel 58, 66 creates rotation of the wheel motor70, 72, thereby enabling power generation for the patient supportapparatus 30. Again, although the wheel 58, 66 rotates, the patientsupport apparatus 30 remains stationary. The contact belt 160 may haveany suitable length and/or width to enable rotation of the wheel 58, 66.

The power transfer device 82 in FIGS. 15 and 16 may be installed intothe floor or may be a unit that is placed on top of the floor surface.The power transfer device 82, transfer motor 148, and mechanicaltransfer element 150 may be configured to rotate the wheel 58, 66 forpower transfer purposes according to embodiments other than those shownin FIGS. 15 and 16.

Any of the aforementioned embodiments of the power transfer systems 80described herein may be utilized individually or in combination. Forexample, the mechanical transfer elements 150 in FIGS. 15 and 16 mayfurther be equipped with electrical sending elements 94 for transferringpower to electrical receiving elements 96 of the wheel 58, 66simultaneously while mechanical rotation of the wheel 58, 66 enablespower transfer to the motor 70, 72. Similarly, the power transfer device82 of FIG. 6 may be equipped with mechanical transfer elements 150 inthe mechanical features 116 upon which the wheel 58, 66 rests.

It will be further appreciated that the terms “include,” “includes,” and“including” have the same meaning as the terms “comprise,” “comprises,”and “comprising.”

Several embodiments have been discussed in the foregoing description.However, the embodiments discussed herein are not intended to beexhaustive or limit the invention to any particular form. Theterminology which has been used is intended to be in the nature of wordsof description rather than of limitation. Many modifications andvariations are possible in light of the above teachings and theinvention may be practiced otherwise than as specifically described.

The invention claimed is:
 1. A power transfer system comprising: apatient support apparatus comprising a support structure having a baseand a patient support surface for a patient and wheels coupled to saidsupport structure to facilitate movement of said patient supportapparatus over a floor surface and wherein one or more of said wheelsincludes a power receiver integrated therewith; and a power transferdevice separated from said patient support apparatus and beingenergizable to interact with said wheel to facilitate power transferbetween said power transfer device and said power receiver through saidwheel.
 2. The power transfer system of claim 1, wherein said powertransfer device comprises a sending coil and wherein said power receivercomprises a receiving coil to facilitate wireless and inductive powertransfer between said sending coil and said receiving coil.
 3. The powertransfer system of claim 1, wherein said power transfer device comprisesa sending electrode and wherein said power receiver comprises areceiving electrode to facilitate wireless and capacitive power transferbetween said sending electrode and said receiving electrode.
 4. Thepower transfer system of claim 1, wherein said wheel comprises one ormore of a tire, a rim, an axle, and a motor, and wherein said powerreceiver comprises an electrical element integrated with one or more ofsaid tire, rim, axle, and motor of said wheel.
 5. The power transfersystem of claim 1, wherein said wheel is configured to rotate about anaxis of rotation and wherein said power receiver comprises one or moreelectrical elements integrated with said wheel and disposed radiallyabout said axis of rotation.
 6. The power transfer system of claim 1,wherein said wheel comprises a contact face for interacting with thefloor surface and wherein said power receiver comprises one or moreelectrical elements integrated with said wheel and with said electricalelement being aligned with said contact face of said wheel.
 7. The powertransfer system of claim 6, wherein said power transfer device comprisesa horizontal member disposed parallel to the floor surface and one ormore electrical elements integrated with said horizontal member suchthat interaction between said contact face and said horizontal memberfacilitates interaction between said electrical element of said powerreceiver and said electrical element of said power transfer device totransfer power.
 8. The power transfer system of claim 1, wherein saidwheel comprises an exterior face that is perpendicular to the floorsurface and wherein said power receiver comprises one or more electricalelements integrated with said wheel and with said electrical elementbeing aligned with said exterior face of said wheel.
 9. The powertransfer system of claim 8, wherein said power transfer device comprisesa vertical member being perpendicular to the floor surface and one ormore electrical elements integrated with said vertical member such saidinteraction between said exterior face and said vertical memberfacilitates interaction between said electrical element of said powerreceiver and said electrical element of said power transfer device totransfer power.
 10. The power transfer system of claim 1, wherein saidpower receiver comprises a wheel motor configured to receive power fromrotation of said wheel.
 11. The power transfer system of claim 10,wherein said power transfer device is energizable to rotate said wheelfor rotating said wheel motor to transfer power.
 12. The power transfersystem of claim 1, wherein said power transfer device is energizable tointeract with said wheel when said wheel is stationary to facilitatepower transfer between said power transfer device and said powerreceiver when said wheel is stationary.
 13. The power transfer system ofclaim 1, wherein said power transfer device is energizable to interactwith said wheel when said wheel is moving to facilitate power transferbetween said power transfer device and said power receiver when saidwheel is moving.
 14. The power transfer system of claim 1, wherein saidpower transfer device comprises a guide mechanism configured tomechanically receive said wheel.
 15. The power transfer system of claim1, wherein said patient support apparatus further comprises an energystorage device coupled to said power receiver and wherein said powerreceiver is configured to provide transferred power to said energystorage device.
 16. The power transfer system of claim 1, wherein saidwheel including said power receiver is one or more of a caster wheel, anactively steerable wheel, and an actively driven wheel.
 17. The powertransfer system of claim 1, wherein said patient support apparatuscomprises four caster wheels and with each caster wheel including saidpower receiver.
 18. The power transfer system of claim 1, wherein saidpatient support apparatus comprises a brake mechanism and a power supplyand wherein said power receiver comprises one or more electricalelements and further comprising a device coupled between said powersupply and said electrical element and wherein said device is actuatedto establish electrical coupling between said power supply and saidelectrical element when said brake mechanism is actuated and whereinsaid device is actuated to prevent electrical coupling between saidpower supply and said electrical element when said brake mechanism isnot actuated.
 19. A patient support apparatus comprising: a supportstructure having a base and a patient support surface for a patient; andwheels coupled to said support structure to facilitate movement of saidpatient support apparatus over a floor surface; and wherein one or moreof said wheels includes a power receiver integrated therewith and withsaid power receiver of said wheel configured to interact with a powertransfer device that is energizable and separated from said patientsupport apparatus to facilitate power transfer from said power transferdevice to said power receiver through said wheel.
 20. A method oftransferring power to a patient support apparatus, the patient supportapparatus comprising a support structure having a base and a patientsupport surface for a patient and wheels coupled to the supportstructure to facilitate movement of the patient support apparatus over afloor surface and wherein one or more of the wheels includes a powerreceiver integrated therewith, and with a power transfer device beingseparated from the patient support apparatus and being energizable tofacilitate power transfer between the power transfer device and thepower receiver through the wheel, the method comprising: moving thepatient support apparatus such that the wheel is adjacent to the powertransfer device; energizing the power transfer device; creatinginteraction between the power transfer device and the wheel; andtransferring power to the power receiver from the power transfer devicein response to interaction created between the power transfer device andthe wheel.